The present invention involves an odorant injection system for a transportation loading dock handling liquified petroleum gas (LPG). More specifically, the system of the present invention uses a pressured gas valving system to inject a measured portion of odorant into the LPG line near the loading arm of a transportation loading dock.
Liquified petroleum gas is practically odorless and highly flammable in an air mixture. It is desirable, if not mandatory, to odorize the LPG to detect leaks in storage vessels, furnaces or stoves which use the LPG. Accordingly, when LPG is transferred from bulk storage to tank trucks, for example, an odorant is added to the LPG. It has long been recognized that an effective amount of odorant is an amount sufficient to warn of a leak but not much more. Over-odorization is not desirable because the odor can be present even absent a leak. For example, a pilot flame may not burn all the odorant. The apparatus of the present invention provides an economical, easy to use and accurate system which provides an accurate record that the tank truck has odorant added to the LPG.
U.S. Pat. No. 2,935,391 discloses an apparatus for odorizing a product. The apparatus includes a supply drum, a pressure cylinder, a stench pot and a vent tank. The vent tank is used to absorb the mercaptan odorant.
U.S. Pat. No. 3,216,434 discloses an additive injection system. The system includes an electrical system which injects a predetermined amount of additive and a printing head which records the amount of additive and the number of injections on a ticket.
U.S. Pat. No. 3,235,348 discloses a system for adding ethyl mercaptan into natural gas or liquified petroleum gas. The system uses a positive displacement metering pump and dual buffering chambers containing lube oil and mercury to cushion the action of the pump.
U.S. Pat. No. 3,907,515 discloses an apparatus for odorizing liquid natural gas. Since LNG is handled at very low temperatures this patent discloses a complex electrical control circuit with automatic shutdown features to add an odorant at very cold (cryogenic) temperatures.
Other patents which disclose the injection of odorants are U.S. Pat. Nos. 1,930,848; 2,098,626; 2,261,590 and 4,025,315.